Diesel fuel



Patented Jan. 22, 1952 DIESEL FUEL Prime 1... Pinotti, Larkspur, Calif., minor to California Research Corporation, San Franclsco, CaliL, a corporation of Delaware No Drawing. Application June 1, 1948, Serial No. 30,522

7 Claims.

The present invention relates to a method of treating high sulfur diesel oil fractions to reduce engine wear incident to their combustion, and

to high sulfur diesel fuel compositions, having inhibited wear characteristics, produced by this method.

, During recent years commercial employment of diesel engines has been greatly extended. Mechanical improvements and refinements have served to adapt the diesel engine to a variety of new uses. These improvements and this increased commercial use of diesel engines have resulted in demands upon petroleum refiners for greater volumes of diesel engine fuel and for the production of diesel fuels of higher quality. Diesel engines in use, range from low speed marine engines which perform satisfactorily on a heavy, relatively crude fuel oil to high speed automotive engines requiring a refined fuel hav ing a cetane number of fifty or above.

The maximum sulfur contents permissible in various diesel fuels are higher than those permitted in gasolines. They range from about 0.25% by weight for an automotive diesel fuel to about 2.0% to 2.5% by weight for marine diesel fuels. The greater proportion of the diesel fuels currently marketed contain between about 0.5% and 1% sulfur by weight.

Engine wear incident to the combustion of diesel fuels has been found to be directly related to the sulfur content of the fuel, the wear rate increasing with the sulfur content. Reduction of the sulfur content of diesel fuels wouldpof course, be desirable from the standpoint of reducing engine wear but the refining methods available for effecting such reduction would entail a considerable expense and their employment would increase fuel costs. Current practice, dictated by economic considerations, is to employ the high sulfur fuels and accept the high engine wear rates incident to their use.

It is an object of the present invention to uti-.

lize a high sulfur diesel fuel stock to provide a diesel fuel having engine wear characteristics comparable to those of low sulfur fuels without recourse to expensive desulfurization treatments.

It has now been discovered that engine wear incident to the combustion of high sulfur fuels may be greatly reduced by extracting petroleum nitrogen bases from cracked and straight-run The comtin contained in the raw crude oil are not extractable by acids. When the crude is distilled, however, it is found that a substantial proportion of the nitrogen content of the crude appears in the naphtha and gas oil fractions of the distillation. The nitrogen compounds contained in the crude are altered in character during. distillation, probably by cracking, and the nitrogen compounds which appear in the distillate fractions may, in part, be extracted with dilute sulfuric acid. These extractable nitrogen compounds are basic in character and have been broadly denominated petroleum nitrogen bases. The term petroleum nitrogen bases," as used herein, includes not only nitrogen base containing extracts from both straight run and cracked stocks but the reaction product obtained by the catalytic hydrogenation of these extracts as hereinafter described. They are believed to contain heterocyclic nitrogen ring compounds including alkylated quinoline and pyridine derivatives, however, precise information concerning structure, individual compounds, and the distribution of the individual compounds in. the extracted material is not available.

The usual method of recovering nitrogen bases from straight-run naphthas or gas oils consists in agitating the oil with about 0.1 to 2 times its volume of 30-50% sulfuric acid. The mixture separates, on standing, into an acid layer containing nitrogen bases and an oil layer. The acid layer is removed and neutralized. The neutralized solution separates, on standing, into an oily upper layer comprising petroleum nitrogen bases and a lower aqueous layer. The upper layer is removed and may be added to high sulfur diesel fuels in the manner hereinafter described. A typical analysis of a nitrogen base containin extract derived from a straight-run California gas oil by extraction with 30% H2804 showed a density of 1.0023, a refractive index M 1.550, a molecular weight 236, and contained 83.3% carbon, 9.6% hydrogen, 5.8% nitrogen and 0.5% sulfur. Nitrogen base containing extracts obtained in the above manner are referred to as straightrun petroleum nitrogen bases. in the subsequent description of the invention and in the appended claims in order to distinguish this material from the other species of nitrogen bases hereinafter described.

Petroleum nitrogen bases undergo further changes in character when the straight-run distillates of the crude, containing nitrogen bases, are subjected to cracking conditions. Again, precise information concerning the changes which occur and the identity of the resultant products is not available. However, the nitrogen bases contained in cracked distillates, such as cracked naphthas and gas oils may be recovered by the same method as that described above for the recovery of nitrogen bases from straightrun distillates. Thenitrogen bases thus recovered from cracked distillates may also be added to high sulfur diesel fuels to reduce engine wear. In the specific description of the manner of their employment contained herein and in the appended claims these nitrogen base containing extracts are referred to as cracked petroleum nitrogen bases.

Either the straight-run nitrogen bases or the cracked nitrogen bases above described may be subjected to catalytic hydrogenation in the manner disclosed in U. S. Patent 2,302,655 to Rutherford. According to the patent disclosure petroleum nitrogen bases, either straight-run or cracked, are contacted with a sulf-active hydrogenation catalyst at 475-535 F. in the presence of approximately 10 times the amount of hydrogen stoichiometrically required for the reduction of the nitrogen bases under a superatmospheric pressure. Dilute sulfuric acid is added to the reaction product to adjust the pH of the mixture to about 9.5. At this pH a phase separation occurs, the lower aqueous phase is removed and neutralized. Upon neutralization an upper phase, comprising reduced nitrogen bases separates from the neutral liquid. This upper phase is removed by decantation. The reduced nitrogen bases, thus formed, may be added to high sulfur diesel fuels to inhibit engine wear.

It will be understood that in the separation of nitrogen bases from either straight-run or cracked distillates dilute acids other than sulfuric acid may be employed, for example hydrochloric or hydrofluoric acids. Further, they may be separated by sulfur dioxide extraction though the extract obtained in this manner will usually contain large quantities of non-nitrogenous material.

A series of tests were run varying the sulfur content and added nitrogen base content of the fuel. The tests were made with a standard Caterpillar D-4400 diesel engine operating at 1200 R. P. M. under 40% load. The jacket temperature was 120 F. and the exhausttemperature was 425 F.

The following table summarizes the results obtained in the tests.

From the table it is seen that substantial reductions in cylinder wear are obtained by the addition of small amounts of petroleum nitrogen bases to the base fuels.

Similar runs were made in a 5%" bore single cylinder Caterpillar engine operated at 920 R. P. M. and at 140% load, the jacket temperature being 175 F. and the exhaust temperature 1200 F. The wear rate under these conditions was somewhat lower with diesel fuels to which no nitrogen bases had been added, such as fuel D-3304 of the table. The decrease in wear rate obtained by the addition of nitrogen bases was very substantial though somewhat lower than that obtained in the runs summarized in the table.

In runs under both sets of conditions, engine deposits were increased by the addition of nitrogen bases to the fuel. The tendency toward increased deposits was greater with reduced and cracked nitrogen bases than with straight-run nitrogen bases. Where the amount of nitrogen bases added to the fuel exceeded the sulfur content, the sulfur content being based on weight per cent and the nitrogen base content on volume per cent of the final fuel, the tendency toward fouling was aggravated.

In order to obtain the desired reduction in engine wear during the combustion of high sulfur diesel fuels without sustaining excessive increases bases are added to the high sulfur diesel fuel in such amount that, in the finished fuel, the volume per cent of nitrogen bases is between about one-half and one and one-half times the weight per cent of sulfur.

The manner in which nitrogen bases accomplished a reduction in engine wear incident to the combustion of high sulfur diesel fuels is not known. The expectation would be that these compounds, upon being injected into the engine 0 in homogeneous mixture with the hydrocarbon fuel, would be burned as the fuel is burned and that such wear reduction as might accrue from their basic character and putative ability to neu- Run No 0-1-8 0-1-12 0-2-11 (1-2-12 C-1-9l0 0-1-13 0-2-13 Test Fuel D-3304 D-3897 D-3870 D-3898 D-3815 D-4097 D4098 Base Fuel l A B C 0 Inspections:

Viscosity SSU 100 F 40. 5 37. 2 37. 6 35. 8 Con.-Cerbon-l0% Bot. 0. 09 0. 02 0. 07 Sulfur Per Cent 0.82 0.71 0.71 0.71 1.15 1. 15 1.15 Nitrogen Bases 0. 01 0. 02 0. O2 0. 02 0. 02 0. 02 0. 02 Distillation ASTM-D86, l0% 473 450 449 450 429 429 435 Distillation ASTM-DBG, 548 514 517 519 513 513 513 Distillation ASIM-D86, 650 623 629 638 595 595 596 Distillation ASTM-D86, EP 700 706 706 712 680 684 675 Added Nitrogen Bases:

Type Reduced Cracked Amount Vol. Per Cent"... None None 0. 33 0.72 None 0.80 0.87 Piston Skirt Deposits, P. D. Number 80 130 30 80 70 Ring Groove Deposits, G. D. N umber' No. 1 Groove 32 24 22 36 31 25 17 No. 2 Groove l3 l2 l8 l3 1 l3 10 Ring Land Deposits... lt/med lt/med lt/med mid/hvy mid/hvy hvy hvy Cylinder Liners clean clean clean clean clean Cylinder Wear, In/1000 hr. x 10 5 6.5 4. 7 3. 9 l. 6 l0. 9 5. 6 2. 8

1 Straight run. I Hard black lacquer and flaky carbon.

tralize acidic combustion products would be lost. Whatever the mechanism of the reduction of engine wear which they produce may be. the re- Two kinds of wear have been described: abrasive wear caused by mechanical sliding of metal surfaces over each other, and "corrosive wear caused by condensation of corrosive acidic materials on cylinder walls. It has been taught that corrosive wear is encountered at temperatures about 120 F. and lower. As indicated above,inclusion of nitrogen bases in a high sulfur fuel substantially reduced engine wear at both high and low jacket temperatures. It would thus appear that both of the types of wear which have been described in the art may be reduced by the addition of nitrogen bases to high sulfur fuels.

:1 claim:

1. A diesel fuel comprising a major proportion of a diesel oil having a, sulfur content between about 0.25% and 2.5% by weight and about onehalf to about one and one-half times the weight per cent of said sulfur of a wear inhibiting agent consisting essentially of a nitrogen base containing extract of a California crude oil distillate boiling within the boiling range of naphtha and gas oil, said extract being separated by the steps comprising extracting said distillate with a dilute mineral acid, separating an acid phase, neutralizing the acid phase with an aqueous alkaline solution, separating an oily phase comprising nitrogen bases from the neutralized acid phase, and water washing said oily phase.

2. A diesel fuel comprising a major portion of a diesel fuel oil having a sulfur content between about 0.25% and 2.5% by weight and a wear inhibiting agent consisting essentially of a nitro gen-base-containing extract of a California nitrogen-base-containing crude-oil distillate boiling within the range of naphtha and gas oil, said extract being separated by the steps comprising extracting said distillate with about 0.1 to 2 volumes of -50% sulfuric acid per volume of distillate, separating an acid phase, neutralizing the acid phase with an aqueous alkaline solution, separating an oily phase comprising nitrogen bases from the neutralized acid phase, and water washing said oily phase, the amount of said wear inhibiting agent being suilicient substantially to reduce engine wear incident to combustion of said diesel oil.

3. A diesel fuel oil composition comprising a major proportion of a diesel fuel oil having a sulfur content above about 0.25% by weight compounded with about one-half to about one and one-half times the weight per cent of said sulfur of petroleum nitrogen bases obtained by extracting nitrogen-base-containing petroleum hydrocarbons boiling within the boiling range of naphtha and gas oil with dilute mineral acid, neutralizing the acid phase from said extraction Itep, and separating an oil phase containing said nitrogen bases from said neutralized acid phase.

4. A diesel fuel oil composition comprising a major proportion of a diesel fuel oil having a sulfur content above about 0.25% by weight and containing about one-half to about one and onehalf times the weight per cent of said sulfur of naturally-occurring nitrogen bases obtained by extracting nitrogen-base-containing straight run petroleum hydrocarbons boiling within the boiling range of naphtha and gas oil with dilute mineral acid, neutralizing the acid phase from said extraction step, andseparating an oil phase containing said nitrogen bases from said neutralized acid phase.

5. A diesel fuel oil composition comprising a major proportion of a diesel fuel oil having a sulfur content above about 0.25% by weight and containing about one-half to about one and onehalf times the weight per cent of said sulfur 'of petroleum nitrogen bases obtained by extracting nitrogen-base-containing cracked petroleum hydrocarbons boiling within the boiling range of naphtha and gas oil with dilute mineral acid, neutralizing the acid phase from said extraction step, and separating an oil phase containing said nitrogen bases from said neutralized acid phase.

6. A diesel fuel comprising a major proportion of a diesel fuel oil having a sulfur content between about 0.25% and 2.5% by weight and about one-half to about one an one-half times the weight per cent of said sulfur of a wearinhibiting agent consisting of a nitrogen-basecontaining extract of a straight-run California crude oil distillate boiling within the boiling range of naphtha and gas oil, said extract being separated by the steps comprising extracting said distillate with a dilute mineral acid, separating an acid phase, neutralizing the acid phase with an aqueous alkaline solution, separating an oil phase comprising nitrogen bases from the neutralized acid phase, and water washing said oil phase.

7. A diesel fuel comprising a major proportion i of a diesel fuel oil having a sulfur content between about 0.25% and 2.5% by weight and about one-half to about one and one-half times the weight per cent of. said sulfur of a wear-inhibiting agent consisting of a nitrogen-base-containing extract of a crackedCalifornia crude oil distillate boiling within the boiling range of naphtha and gas oil, said extract being separated by the steps comprising extracting said distillate with a dilute mineral acid, separating an acid phase, neutralizing the acid phase with an aqueous alkaline solution, separating an oil phase compris ing nitrogen bases from the neutralized acid phase, and water washing said oil phase.

PRIMO L. PINOTTI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,524,674 Sadtler Feb. 3, 1925 2,035,583 Bailey 1L Mar. 31, 1936 2,198,961 Dietrich Apr. 30, 1940 2,433,243 Smith Dec. 23, 1943 

1. A DIESEL FUEL COMPRISING A MAJOR PROPORTION OF A DIESEL OIL HAVING A SULFUR CONTENT BETWEEN ABOUT 0.25% AND 2.5% BY WEIGHT AND ABOUT ONEHALF TO ABOUT ONE AND ONE-HALF TIMES THE WEIGHT PER CENT OF SAID SULFUR OF A WEAR INHIBITING AGENT CONSISTING ESSENTIALLY OF A NITROGEN BASE CONTAINING EXTRACT OF A CALIFORNIA CRUDE OIL DISTILLATE BOILING WITHIN THE BOILING RANGE OF NAPHTHA AND GAS OIL, SAID EXTRACT BEING SEPARATED BY THE STEPS COMPRISING EXTRACTING SAID DISTILATE WITH A DILUTE MINERAL ACID, SEPARATING AN ACID PHASE, NEUTRALIZING THE ACID PHASE WITH AN AQUEOUS ALKALINE SOLUTION, SEPARATING AN OILY PHASE COMPRISING NITROGEN BASES FROM THE NEUTRAILZED ACID PHASE, AND WATER WASHING SAID OILY PHASE. 